Strokes, head injuries and other conditions can cause dementia, but the main cause is Alzheimer's disease. Roughly one in 10 people older than 65 has Alzheimer's; about half of people older than 85 have it.

No cure for Alzheimer's exists, but medications can slow its progress. Early diagnosis is critical. General practice doctors sometimes make an initial diagnosis, but experts recommend testing by a neurologist, psychiatrist or diagnostic clinic.

A complete diagnosis should include blood work and other lab tests because vitamin deficiencies, thyroid disease and other curable conditions can create symptoms that mimic dementia.

Ask yes or no questions. Wrong: "What would you like to do today?" Right: "Would you like to go for a walk?"

Break instructions into pieces. Wrong: "Go get undressed." Right: "Come into the bedroom, please. (pause). Take off your shirt (pause). Take off your pants."

Don't explain yourself. Wrong: "I bought apples on sale. They went brown, so I made a pie." Right: "I made an apple pie. Do you want some?"

Don't try to orient them to reality. Wrong: "This is your home now. You haven't lived in Michigan for 15 years." Right: "Isn't Michigan beautiful in the fall? We can go there as soon as I buy airline tickets. Do you want some ice cream?"